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Version: 2.0.x

Execution Strategy

ZIO Test has two different strategies to run members of a test suite: sequential and parallel. Accordingly, there are two test aspects for specifying the execution strategy:

Parallel​

The default strategy is parallel. We can explicitly enable it using TestAspect.parallel:

import zio._
import zio.test.{ test, _ }

suite("Parallel")(
  test("A")(Live.live(ZIO.attempt("Running Test A").delay(1.second)).debug.map(_ => assertTrue(true))),
  test("B")(ZIO.attempt("Running Test B").debug.map(_ => assertTrue(true))),
  test("C")(Live.live(ZIO.attempt("Running Test C").delay(500.millis)).debug.map(_ => assertTrue(true)))
) @@ TestAspect.parallel

After running this suite, we have the following output:

Running Test B
Running Test C
Running Test A
+ Parallel
  + A
  + B
  + C

To change the degree of the parallelism, we can use the parallelN test aspect. It takes the number of fibers and executes the members of a suite in parallel up to the specified number of concurrent fibers.

Sequential​

To execute them sequentially, we can use the sequential test aspect:

import zio._
import zio.test.{ test, _ }

suite("Sequential")(
  test("A")(Live.live(ZIO.attempt("Running Test A").delay(1.second)).debug.map(_ => assertTrue(true))),
  test("B")(ZIO.attempt("Running Test B").debug.map(_ => assertTrue(true))),
  test("C")(Live.live(ZIO.attempt("Running Test C").delay(500.millis)).debug.map(_ => assertTrue(true)))
) @@ TestAspect.sequential

And here is the output:

Running Test A
Running Test B
Running Test C
+ Sequential
  + A
  + B
  + C